The disclosure relates to an electrode for an energy accumulator, in particular a lithium-based energy accumulator and a method for manufacturing such an electrode. The present disclosure also relates to a lithium-ion battery.
Lithium-ion batteries are known as energy accumulators with a very high energy density for multiple applications. In addition to applications in laptops, smart phones etc. such batteries play a significant role in the electrification of automobiles. However, currently achievable energy contents of the batteries with an acceptable battery weight permit only limited ranges and a restricted service life, expressed in cycles.
Lithium-ion batteries, for example lithium-sulfur batteries, comprise essentially a cathode, an anode, a separator arranged between the cathode and the anode and an ion-conducting electrolyte. Lithium-containing anodes, which, compared to carbon anodes which intercalate lithium have a higher energy density with respect to the weight and the volume and are therefore extremely lightweight, are known from the literature. However, the reactivity of lithium and the associated restricted service life, the formation of dendrites, the electrolyte compatibility, its manufacture and safety problems proved disadvantageous for wide use.
Separation of the lithium anode from the electrolyte is aimed at in order to avoid a reaction with the electrolyte during the recharging, so as to avoid the formation of dendrites and of resistance barrier layers on the anode. The resistance barrier layers give rise to an increase in the internal resistance of the battery and to a worsening performance.
Previously, there were a large number of solutions for protecting the lithium anode, including coating the lithium anode with a protective layer made of polymers, ceramics or glass, wherein the protective layer for the lithium ions is conductive. However, the applied protective layer results in the problem of the ionic conductivity being greatly reduced by the boundary layer resistance between the lithium and the protective layer. In the course of the service life of a correspondingly protected lithium anode, the boundary layer resistance continues to increase, particularly since the sharply formed dividing line between the material of the lithium anode and the protective layer gives rise to worsening adhesion, which has an adverse effect on the ionic conductivity.
US 2002/0012846 provides an overview of known solutions for protecting lithium anodes, including coating the lithium anode with an intermediate layer or protective layer. Furthermore it is disclosed that an anode comprises a substrate and an active anode layer which comprises a reaction product of a lithium metal, which is deposited on the substrate together with one or more reactive gaseous materials. The reactive gaseous materials are selected from carbon dioxide, nitrogen, sulfur dioxide, saturated and unsaturated hydrocarbons. In addition, one or more individual-ion-conducting layers are generated which form, as a boundary surface layer, a protection layer which provides stabilization with respect to the anode. Also, the individual layers form precise dividing lines here.
Although a multiplicity of intermediate layers and/or protective layers for lithium anodes have been proposed previously, there continues to be a need for improved electrodes and simplified methods which permit easier manufacture of corresponding batteries with a long service life, high lithium cycling efficiency and high energy density.